416 STATE BOARD OF AGRICULTURE. 



Molds and yeasts are not in the cream in large quantities, though they 

 are regular habitants of ordinary butter. Hastings (Wise. Sta. Report, p. 

 107, 1906) found lactose fermenting yeasts in about J of all butter samples. 

 Will says in Lafar's Handbuch der Technischen Mykologie, Bd. 4, p. 285: 

 "The Torulacege find lodgment in all kinds of organic substances and often 

 develop there to a really surprising extent. Milk, butter and cheese give 

 them favorable conditions. Their main habitats are the creameries and all 

 kinds of fermentation industries, and the organisms are not only found in 

 the raw material and in the products made from it in all the different stages, 

 they are also in the air of all rooms, on the walls of the fermenting and stor- 

 ing rooms, as well as on the utensils, in perfectly enormous abundance." 



Tliis might explain the large percentage of wild yeasts that we found in 

 our samples to be the most regular micro-organism besides the lactic acid 

 bacteria. 



Esten's publications about the sources of bacteria in milk give a good 

 review of the latest investigations in this question and bring out some new, 

 interesting points. 



THE INFLUENCE OF MICRO-ORGANISMS UPON BUTTER. 



The most interesting result of our chemical analyses of butter is certainly 

 the fact that samples which are scored rancid or even very rancid did not 

 have the slightest increase of acidity. This seems to indicate that ran- 

 cidity of cold storage butter is not connected with a hydrolysis of fat in the 

 ordinary way, and for the same reason cannot depend upon decomposition 

 products of glycerine. It seems improbable that fat should be decomposed 

 in any other way, since we cannot conceive of an oxidation in the interior 

 of a 60 lb. butter tub, and an anaerobic decomposition is almost impossible 

 because of the lack of oxygen in the fat molecule. 



Our investigations for fat spatting organisms were made in the following 

 way: We made litmus agar from sugar-free broth (standard methods. Jour. 

 Inf. Dis. Supp. No. 1, p. 107) and added a few drops of pure butter fat to 

 each agar tube. The fat agar was sterilized as usual and, after the last 

 heating, shaken violently in order to distribute the fat through the whole 

 medium and was slanted. If fat-splitting bacteria are inoculated on this 

 litmus fat agar, the free fatty acids will turn the litmus red. Other decom- 

 positions, which might produce acids, can hardly be expected in this medium. 

 By this method we found just four micro-organisms from fresh butter, 

 namely Oidium ladis, a Bacterium and a Coccus, which were found only 

 once, and the orange variety of Micrococcus lactis varians, but only one out 

 of eleven had split fat. It is, however, easily possible that many other 

 micro-organisms lost their fat-splitting qualities by the cultivation on fat- 

 free media. 



It is worth wliile mentioning that the four normal samples with high 

 aciditv, II, XI, XIII, and XXI, have a very high number of Oidium lactis. 

 The fat-splitting qualities of this mold are well known. The rancidity of 

 these samples might be due to the decomposition of fat. It is a question 

 as to what causes the rancid taste in the other samples. If the fat is not 

 decomposed, there can be nothing but the lactose or the proteids. The 



